1. Field of the Invention
The invention relates to a power output apparatus, a control method thereof, and a vehicle equipped with the power output apparatus.
2. Description of the Related Art
For example, Japanese Patent Application Publication No. 2001-20788 (JP-A-2001-20788) describes a power output apparatus installed in a vehicle, which, under a predetermined deceleration condition, prohibits learning of a control amount obtained during an idle operation of an engine. In this apparatus, unpleasant vibration and engine stalling are prevented by prohibiting learning of an idle control amount and reduction correction of a bypass intake air amount via an ISC valve upon establishment of a deceleration condition in which a difference between an engine speed that has decreased due to a fuel cut and a target idle rotation speed is greater than a predetermined value.
In a power output apparatus in which a drive shaft, an output shaft of an engine, and a rotary shaft of a generator are connected by a planetary gear mechanism or the like, and which is capable of outputting power to the drive shaft using only power from an electric motor connected to the drive shaft, an idle control amount may be learned by causing the engine to perform an idle operation while power is output to the drive shaft using only power from the electric motor. However, during deceleration or the like, i.e. when the rotation speed of the drive shaft varies, this rotation variation in the drive shaft affects the output shaft of the engine, and as a result, the idle control amount may be learned erroneously.